Fat liquoring agent consisting of an epoxy compound and an acid containing ester



United States Patent Us. or. Cll4c 11/00 US. Cl. 8--94.23 14 Claims ABSTRACT OF THE DISCLOSURE A process for fatting leather which is carried out by immersing the leather into a fatting agent consisting essentially of a mixture of (a) an epoxidation product of a polyester of a polyhydric alcohol and an unsaturated aliphatic fatty acid, and (b) an ester of a polycarboxylic acid and an aliphatic alcohol.

This invention relates to a fatting agent for leather and to a process for applying same.

Fatting agents are introduced onto the fibers of leather during a wet process so that drying may be effected without cohesion of the fibers of leather during drying. Preventing such a cohesion prevents the fibers from sticking together and gives more life to the leather, since the leather fibers may move freely back and forth against each other. When the leather is dry, friction is also prevented by the fatting agent, permanently preventing adhesion of the fibers.

In general, natural fatty substances have been used as fatting agents in the preparation of leather to achieve the necessary softness and suppleness. Such natural fats and oils include for example, lard oil, sheep oil, neatsfoot oil, corn oil, cottonseed oil, olive oil, castor oil, cod oil, sperm oil and others. The substances are generally applied as an oil in water emulsion and are present in the pores of the leather essentially in unbonded form. Consequently,

they tend to migrate and, especially under thermal and mechanical influences, travel to the surface of the leather where they may sweat out. For instance, these migrating fats interfere in modern methods of shoe manufacture, where the rubber sole is bonded to the leather upper by vulcanization at elevated temperatures.

It has already been attempted to achieve an improved bond of the fatting agent to the leather fiber by using epoxidized fats or oils. However, these agents do not react to an adequate degree with the collagen of the leather fiber under the conditions customarily used in leather finishing. Even an additional thermal treatment achieves only a minor increase in the bonding of the fat.

It is an object of this invention to provide a novel fatting agent that overcomes the afore-mentioned disadvantages of the prior art.

Another object of this invention is to provide a fatting agent that adheres to the leather fiber to provide a pr duct having superior softness and suppleness.

A further object of this invention is to provide a process for fatting leather using a novel fatting agent.

Another object of this invention is to provide a fatting agent for leather consisting essentially of a mixture of: (a) an epoxidation product of a fatty substance, said product containing more than one epoxide group in the molecule, and (b) a compound containing at least two free acid groups and at least one high molecular weight radical having from about *8 to 36 carbon atoms.

These and other objects and advantages will become apparent as the description proceeds.

Accordingly, the subject matter of the present invention is a fatting agent consisting essentially of a combination of: (a) epoxidation products of fatty substances, said products containing more than one epoxide group in the molecule, and (b) compounds containing at least two free acid groups as well as one or more high-molecular Weight radicals having from 8 to 36, and preferably 12 to 18, carbon atoms. Components (a) and (b) must be miscible with each other. The epoxidized fatty substances of group (a) are primarily obtained by epoxidation of natural unsaturated fats and oils, such as sperm .oil, soybean oil, olive oil, codliver oil, tallow, lard oil,

sheep oil, neatsfoot oil, wool grease, corn oil, cottonseed oil, castor oil, oiticica oil, palm oil, coconut oil, rice bran oil, menhaden oil, sardine oil, red fish oil, herring oil, etc. Since glycerin is common to the structure of all fatty oils, the difference among them exists in the chemical nature of the fatty acids which combine with glycerin. Generally, the above natural fats and oils contain unsaturated fatty acids having from 8 to 20 carbon atoms. In similar fashion, the corresponding epoxidation products of synthetic diand poly-esters of polyhydric alcohols containing 2 to 6 carbon atoms, such as glycols, glycerin, polyglycols, sugar alcohols, pentaerythrite and the like, with unsaturated fatty acids containing 8 to 20 carbon atoms may be used. In addition, the epoxidation products of diand poly-esters of polycarboxyl acids having from 2 to 8 carbon atoms, such as oxalic acids, maleic acid, citric acid and phthalic acid, with unsaturated fatty alcohols having from 8 to 20 carbon atoms may also be used. For the ester formation, primarily the unsaturated fatty acids obtained from natural fats, such as oleic acid, linoleic acid, linolenic acid and ricinenic acid (9,1l-linoleic acid), or mixtures of these fatty acids obtained from natural fats, as well as the unsaturated fatty alcohols prepared therefrom in known fashion may be used.

The epoxidation of the above fatty substances is accomplished in known fashion, for instance, with peracids, such as performic acid, peracetic acid, and the like. Depending upon the type of starting materials and upon the manner of carrying out the reaction, the double bonds present in the starting material are substantially transformed into epoxide groups. For use according to the present invention those products are suitable which con tain, on the average, more than one and preferably more than 1.5 epoxide groups per molecule. The fatty substance may have up to 8.5 percent by weight of epoxide oxygen content. The compounds defined as (a) are well known in the art and hence no claim is made specifically thereto.

The high molecular Weight compounds of group (b) which contain at least two free acid groups in the molecule are derived from aliphatic, aliphatic-cycloaliphatic, or aliphatic-aromatic compounds which have at least one alkyl radical of 8 to 36, and preferably 12 to 18 carbon atoms. The radicals may be branched chain or unsaturated radicals and may be substituted with customary substituents, such as hydroxyl groups. The acid groups are primarily carboxyl groups. These carboxyl compounds may, however, be partially replaced by those organic phosphoric acid derivatives which contain phosphoric acid ester or phosphonic acid groups in the molecule. The portion of the phosphoric acid derivatives in the total amount of compounds containing the acid groups should not exceed 10% by weight.

Examples of compounds of group (b) containing acid groups are the partial esters of triand higher polycarboxylic acids containing two or more free acid groups, especially of citric acid, formed with higher molecular weight alcohols, such as mono-oleyl citric acid ester, mono-2-octyldodecyl citric acid ester, mono-isotridecyl citric acid ester, and the like. The triand higher polycarboxylic acids useful for purposes of this invention may have from 6 to 12 carbon atoms. The higher molecular weight alcohols may have from 8 to 20 carbon atoms. Further suitable as compounds of group (b) are dior higher polycarboxylic acids substituted with high molecular weight hydrocarbon radicals, such as N-dodecylasparaginic acid, N-oleyl-citric acid mono-amide, octyladipic acid, oleylmalonic acid, and the like. The dior higher polycarboxylic acids may have from 8 to 36 carbon atoms. Examples of suitable organic phosphoric acid derivatives are the mono-alkyl esters of orthophosphoric acid formed with high molecular weight alcohols having from 8 to 20 carbon atoms, such as isotridecyl alcohol, oleyl alcohol, etc. Suitable mixtures of compounds containing both carboxyl groups and phosphoric acid groups consist, for example, of citric acid monooleyl ester, and dodecyl alcohol-phosphoric acid monoester.

The fixation of the mixtures consisting of components (a) and (b) in the leather is based upon the fact that the epoxidized fatty substances enter into a reaction with the compounds containing the acid groups to form more or less high polymeric polyester-type products. The reaction proceeds slowly at room temperature, but it may be substantially accelerated by the application of elevated temperatures as well as with the aid of catalysts, such as amines.

The fatting agent mixtures are generally employed as aqueous 10 to 20% emulsions, possibly with the addition of emulsifying agents, or as organic solutions. The agents thoroughly penetrate into the leather, where the reaction which forms the polyester compound takes place. The mixtures are, as a rule, not storable over long periods of time because the reaction proceeds even at room temperature, and they must therefore generally be prepared just prior to their employment by admixing the components.

The mixture ratio between the epoxide fatty substance and the compound containing the acid groups is normally selected so that as complete a reaction as possible may take place between the reacting groups. However, good results are also obtained, especially an increase of the dynamic water-resistance of the leather, when one deviates from equivalent ratios, as where an excess of free acid groups may be present.

The ratio of the number of epoxide groups to the number of acid groups should preferably be from about 1:1 to 1:2.

The fatting agent mixtures are worked into the leather EXAMPLE I A normally fatted chrome-tanned leather with a constant of 6.5% of extractable fat was immersed for minutes into a solution consisting of Parts by weight Citric acid mono-oleyl ester 10.0

Epoxide soybean oil, epoxide oxygen content 6.0% 8.8 Gasoline, B.P. 110140 C 81.2

After drying, the fat content of the leather, determined by solvent extraction, was 15.4%, and after heating for hours at 80 to 90 C. it was 5.9%.

EXAMPLE II 'A chrome-tanned leather was neutralized in customary fashion with 1% ammonium bicarbonate and was then fat-liquored at 60 C. with 11% pure fat in 200% solution, based upon the shaved weight of the leather. After conclusion of the fatting treatment, the leather was acidified with 0.5% formic acid. The fat-liquoring so ution consisted of an emulsion c mposed of the following mixture:

Parts by weight Citric acid mono-oleyl ester 38.0

Epoxide soybean oil, epoxide oxygen content 50% coconut fatty alcohol sulfate paste 30.0

After drying of the leather, 14.4% of fat were found by extraction. After heating the leather for 12 hours at C., the extractable fat content was reduced to 4.5%.

EXAMPLE III A leather prepared as in Example II was fat-liquored with 5% pure fat in 200% solution. The fat-liquoring oil had the following composition:

Parts by weight Citric acid mono-oleyl ester 41.0 Epoxidized fishtrain oil, epoxide oxygen content 5.9% 32.0 Fatty alcohol (C -C phosphoric acid monoester 3.0 Castor oil, sulfated, 30% 1.5 Concentrated ammonia solution 5.5

Water 17.0

The air-dried leather had an extractable fat content of 8.9% After heating at 90 C. for 12 hours the extractable fat content was reduced to 2.9%.

'EXAMPLE IV A mixture of 37.0 parts by weight of monocitric acid ester of 2-hexyl-decanol-1, 33.0 parts by weight of epoxide soybean oil (epoxide oxygen content 6.0% and 30 parts by weight of a 50% coconut fatty alcohol sulfate paste as emulsifier were emulsified in water. A chrome-tanned leather, which had been tanned and neutralized in customary fashion, was fat-liquored at 60 C. with 8% of the fat mixture in 200% of solution.

Immediately after drying the leather, 10.4% of fatting components could be extracted with methylene chloride, and after 6 weeks of storage only 3.2% could be extracted.

EXAMPLE V A fatting agent mixture of 49.0 parts by weight of monocitric acid ester of 2-octyl-dodecanol-l and 41.0 parts by weight of epoxide soybean oil (epoxide oxygen content 6.1%) was admixed with 3 parts by weight of the phosphoric acid mono-ester of the fatty alcohol (C C monoglycol ether, and 7 parts by weight of concentrated ammonia.

A chrome-tanned calf leather was first neutralized, then fat-liquored with 6% pure fat in 200% solution at 60 C. and finally acidified with 0.5% formic acid.

Immediately after drying the leather, 10.7% of fat was extracted from the liquor, but after storage for 6 weeks only 3.4% could be extracted.

EXAMPLE VI A mixture of 11 parts by weight of citric acid monooleyl ester and 8.8 parts by weight of epoxide soybean oil (epoxide oxygen content 6.1%) was admixed with 0.65 part by weight of concentrated ammonia solution. A leather tanned in customary fashion with a chrome tanning agent was fat-liquored with 6% of the above mixture in 200% of solution at 60 C. The mixture was satisfactorily emulsifiable in water. Immediately after drying, 9.8% of fatting components could be extracted from the leather with methylene chloride. After a storage period of 8 weeks the content of extractable fat was reduced to 2.8% without changing the appearance and feel of the leather.

'EXAMPLE VII A leather prepared as in Example II was fat-liquored for one hour at 60 C. in 8% pure fat in 200% solution, based upon the shaved weight of the leather. The fatliquoring solution was prepared by diluting the following emulsion:

Parts by weight Citric acid mono-oleyl ester 31.8 =Epoxide linseed oil, epoxide oxygen content 8.5% 37.5 Water 29.2 Ammonia, 25% 1.5

The air-dried leather immediately after the fat-liquoring treatment had an extractable fat content of 9.6%, which was reduced to 4.0% after heating the leather at 50 C. for 24 hours. After a storage period of 8 weeks without add iytional heating, the content of extractable fat was 3.3 o.

The run was repeated except that the mono-oleyl citric acid ester was replaced by a corresponding amount of octadecenyl succinic acid, N-octadecenyl-asparaginic acid and mono-isotridecyl-dicitric acid ester. Essentially the same results were obtained.

While certain specific examples and preferred modes of practice of the invention have been set forth it will be understood that this is solely for the purpose of illustration and that various changes and modifications may be made without departing from the spirit of the disclosure and the scope of the appended claims.

I claim:

1. A process for fatting leather which comprises immersing leather into a fatting agent consisting essentially of a mixture of:

(a) an epoxidation product of a polyester of an unsubstituted polyhydric alcohol containing from 2 to 6 carbon atoms and an unsaturated unsubstituted aliphatic fatty acid containing from 87m 20 carbon atoms, said product containing more than one epoxide group in the molecule and less than 8.5% by weight of epoxide oxygen, and

(b) an ester, containing at least two free carboxylic acid groups, of an unsubstituted, aliphatic polycarboxylic acid containing from 6 to 36 carbon atoms and an unsubstituted aliphatic alcohol containing from 8 to 20 carbon atoms, ratio of the number of epoxide groups in component (a) to the number of acid groups in component (b) is in the range of 1:1 to 1:2; and thereafter removing said leather from said fatting agent.

2. A process according to claim 1, wherein (a) is an epoxidation product of a member selected from the group consisting of natural fats and natural oils.

3. A process according to claim 1, wherein (a) contains more than 1.5 epoxide groups per molecule.

4. Process of claim 1 wherein up to 10% of component (b) is replaced by an alkyl ester of phosphoric acid and said aliphatic alcohol.

5. Process of claim 4 wherein said ester is a monoalkyl ester of orthophosphoric acid.

6. A process according to claim 1, wherein component (b) is a mono-ester of a fatty alcohol with citric acid.

7. A process according to claim 1, wherein an excess of component (b) is present.

8. Process of claim 1 wherein said polycarboxylic acid contains from 6 to 12 carbon atoms.

9. Process of claim 8 wherein said polycarboxylic acid contains three or more carboxylic groups.

10. Process of claim 1 wherein said ratio is suflicient to effect a complete reaction between the reactive groups.

11. Process for fatting leather, which comprises immersing leather into a fatting agent consisting essentially of a mixture of:

(a) an epoxidation product of a polyester of an unsubstituted polyhydric alcohol containing from 2 to 6 carbon atoms, and an unsaturated unsubstituted aliphatic fatty acid containing from 8 to 20 carbon atoms, said product containing more than one epoxide group in the molecule and less than. 8.5% by weight of epoxide oxygen, and

(b) an ester, containing at least two free carboxylic acid groups, of an unsubstituted aliphatic polycarboxylic acid containing from 6 to 12 carbon atoms, and an unsubstituted aliphatic alcohol containing from 8 to 20 carbon atoms, ratio of the number of epoxide groups in component (a) to the number of acid groups in component (b) is in the range of 1:1 to 1:2; removing said leather from said fatting agent; and curing said leather whereby components (a) and (-b) form a polymeric product.

12. A process according to claim 11, wherein said curing is conducted at room temperatures.

13. A process according to claim 11, wherein said curing is conducted at elevated temperatures.

14. Process of claim 11 wherein said ratio is sufficient to effect a complete reaction between the reactive groups.

References Cited UNITED STATES PATENTS 2,822,235 2/1958 Heyden et al. 894.23 2,872,428 2/1958 Schroeder 117--142 X 3,050,480 8/1962 Budde.

3,291,557 12/1966 Neher et al. 894.23 X 3,101,238 8/1963 Plapper et al. 894.23

LEON D. ROSDOL, Primary Examiner M. HALPERN, Assistant Examiner US. Cl. X.R. 

